Due to pin-out differences (a TCXO needs power), I assume this is for a custom teensy design? If so, I'd encourage you to design it to use a VCXO. This would allow software to trim for even better performance.
I should have caught that. Thanks. This is for a new design. Work on a time synchronization field demo and the outside temperature changes require a TCXO. I'm afraid that the boot loader would have to change to support a TCXO. Based on how I read the mk20dx256 manual it looks like a TCXO would have to use the EXTAL pin and the external clock reference bit would have to be set. Do you agree that the boot loader would have to change to support a TCXO?